I really really need help: candling mystery

Hi everyone, I just joined this site! I really need help with something.

I found an egg by my car, it looks like a cedar waxwing egg. The egg had a tiny (just a couple millimeters), very shallow chip near the pointed end but the rest looks great.

I really didn't think I could do anything about it, I thought maybe it was a goner for sure. I couldn't find any egg nests in the bushes or surrounding trees. I took it inside and called all the local rescues. No one would take a baby bird before hatching. So my concern got the best of me and I learned how to candle. I read everything I could find online about egg candling and I can't quite figure out what I'm seeing.

When I first looked at it, keeping it warm with a slightly humid, clean towel, it had a detached air cell but the inside didn't look scrambled. The yolk looked fine. Judging from what I've seen online it seems to be only a day or two old, freshly laid. No spidery blood vessels yet. I went out straightaway and bought a small desk incubator.

So it has been in the incubator a couple days. I dripped the tiniest bit of wax on the chipped area, really really carefully to seal it. I know that I shouldn't candle it often but I had to keep checking to see if it was at all capable of developing. The "yolk" has grown in size, almost double what it used to be. I can't really see any vessels forming...the egg is blue with brown spots so it's really hard to see through. Leaving it in the incubator helped with the air cell, which has fused together and may reattach to the side of the egg again.

So what I'm actually concerned about is what I'm seeing inside the shell surface. It looks similar to maybe a blood ring or an air cell but not ...really. Yesterday it was a small (1 centimeter) ring on the side of the egg. Not going all the way around the egg, but like an oval stamped to the inside of the shell. It's very light, not really brown or red. Kinda like the subtly of an air cell. Today I looked at it and it has spread in length to most of the side of the egg, still oval shaped. The "yolk" was bigger today too.

Does anyone have any idea of what I could be seeing? Can blood rings form before you notice veins at all? Can an egg have 2 air cells? Is it something else?

I will try to get a photo next time I candle...maybe next Friday. I want to let it sit for a while and...hang in there if it's still alive. I could really use some help, if you can ask your friends too that would be wonderful.

I really want to save this baby if I can so I can deliver it to animal rescue & rehabilitation. I would lose sleep if I didn't try my best.

Thank you SO much for taking the time to read this. I know it's a lot but I'm doing the best I can to make right by this potential baby birdy.